Machine for making welded tubes



Sept. 21, 1926.

G. A. LINDGREN- v manna. FOR MAKING wnmnn 'ruass Original Filed July 1.1921 2 Sheets-Sheet l G. A. LINDGREN MACHINE FOR MAKING WELDED TUBESOriginal Filed July 1; 1921 2 Sheets-Sheet 2 Patented Sept. .21, 1926.

GUSTAF ABRAHAM nrnn'ennn,

or sonERFons, SWEDEN.

MACHINE FOR MAKING, wnnnnn' TUBES.

Application filed July 1, 1921, Serial No. 481,941, and in Germany Myinvention relates to the shaping and welding of tubes from strips ofmetal. In plants used for this purpose hitherto, the prepared strips ofsheet metal are drawn out of the heating'furnace or oven by means oftongs, or by hooking them on uniformly moving chains. The strips arethereupon passed through drawing dies in which they are bent to a tubeform and are pressed together at their two longitudinal edges and thuswelded. Owing to the substantially uniform movement. of the drawingchain, heavy shocks are produced especially on the entry of thetubewblanks into the drawing dies, resulting. very often in damage anddis arrangement of the plant, while also the stripsare frequently torn.Very high costs a for repairs and losses may thus be incurred.

non-uniformly and in such a way In addition to' this, the hooking of thetongs nto quickly running chains is rather difiicult. so thatinterruptions may occur, resulting in overheating of the sheet metalstrips;

These disadvantages are overcome by the present invention: This isattained bycausing the drawingtongs to' be moved, notas hithertouniformly and: continuously, but

that they grip the workpieces slowly and introduce them into thedrawing'die without'shock, and only. after this do they gradually in.-crease in speed up to that hithertoausual, or to a still greaterfworkingspeed; This nonuniform movement is best attained by effecting theactuation .of the drawing tongs or their equivalent,- '.or' of thedrawing head carrying these tongs, by means'of a fluid, for example airor the :like,whi'ch' enters a cylinder behind a piston whose rod carriesthe drawing head. Moreovenj; with compressed air or the like, aresilient driving medium is provided which takes up like a spring allshocks during the drawing, caused for example by unequal breadths of thestrip. 1

In the drawings aflixed to this specification and forming part thereof,a drawing plant embodying my invention is illustrated by way of example.In the drawings Fig. 1 is a plan view and Fig. 2 a cross section, drawnto a larger scale.

Fig. 3 is a partialplan and Fig. 4 is a rear view.

Beside a heating furnace at are arranged on a bed holders-thepartsattached toit q and .-s'trip-)] so, that; the strip 00 isintroduced without shockand vibration into the draw for the drawing diesc,

May 1?, 191's. Renewed A'ugust' heads 9, h The draw- The cylofcontainers 1", s, which are partly'filled with liquid and are connectedat their upper ends by pipes 3, l comprising a two-way cock 7 with acompressed" air supply pipe 2'. The rods 2', 7care' supported in'theirmovements by, rollers 25 disposed at intervals in the bed bi; The bed.is also formed with guidewflanges u which" are embraced. by the drawingheads 9, h (Fig; 2); The whole bed 6 canbe oscillated about a pivot 11;

(Fig. 1'). f

The strips of sheet meta-Ito beop erated upon are heated in the furnaceaand are bent together at-the one end into a somewhat pointed form fortheepurpos'e ofl facilitatmg their introduction into the drawing. dies0; The strip; xlying infrontof the-drawhead. it is gripped by the tongs7 over which a'drawingz die is passed, the tongs are engaged inthe-eyelet offthe drawing "head h and drawn-slowly into f the dieholder.

This, movement is effected by introducing compressed air or theli-l'rexa bove-theliquid v level inthe container ,8, whereby theliqjuidis-forc'ed through thepipe 1 into the cylinder m. In conseq-uenoe'ofthisrtlre piston with the rod 70 and moves slowly backwards drawinghead, tongs 1ng die, which latter has come to bear in the meantimeagainst the die holder. When this has taken liquid is gradually madelarger and larger, the consequence of which is that the piston incylinder m moves more and. more quickly backwards, so that the, actualdrawing op eration takes place at a comparatively high speed.

y In its movement the piston forces out" the liquid behind it in thecylinder m,'through the pipe 0, into the cylinder'l, causing the pistonin this latter, the rod iand the drawing head g to bemovedtoward thefurnace at. Theliquid in front of the piston in the, cylinplace thepassage for the der Z is thereby forced back again into the container r.The drawing head 9 thus comes into the position in which a further stripcan be seized, while the strip held by the tongs f has been drawn in themeantime completely through the drawing die and has thus been made intoa tube. This tube is then freed from the drawing head it, and is carriedby a transport band in the groove 12 of the bed (Fig. 2) to acalibrating roller mill (not shown). v

Afterthe other tongs, upon which a drawing die has been thrust, havegripped a further strip, and have been drawn back into the drawing head9, liquid is introduced from container 1" into same manner as abovedescribed for the cylinder m, whereby the piston in cylinder Z is movedbackwards with a gradually increasing speed, while the piston in thecylinder m is conducted in the opposite direc tion toward the furnaceris the strips which previously lay in with the two drawing heads havebeen removed, the whole bed?) is now turned about its pivot to in such amanner that the tongs f come opposite the next strips in the fur- .nace,and can grip the same.

There may be any number of cylinders arranged on the bed I) and thecylinders may be supplied with any other suitable pressure mediuminstead of liquid acted upon by compressed air. 7

Instead of the movement being efiected by means of pistons and pistonrods any other method of driving can be used, provided that it iscapable'of being so controlled automatically or set in operation, thatthe movement of the drawing head can take place at a variable speed asdescribed. I

- My invention is distinguished from previous devices of this kind inwhich two separate electric motor engines were used for the purpose ofproducing two different speeds in the different stages of the weldingoperation by the fact that in my invention I provide means of effectinga gradual increase of power, and a cushioningaction by the cylinder Z inthe the furnace in line.

the use of'a motor fluid and a cushion of liquid, and I am therebyenabled to perform a much smoother operation of the working parts and amore eflicient prevention of shocks and arring and jerking movementsthan it is possible to produce by means of 1ndependently operatingelectric. motors having no provision whatever for the gradual swellingup of the power, which is a point of high importance for the preventionof the violent impact of the'blanks against the forming devices andagainst the undue cropping of the edges of the tubes.

I wish it to be understood desire to be limited to the exact details ofconstruction shown and described, for obvious modifications will occurto a person skilled in the art. I

I claim:

1. In a sheet metal tube drawing plant 7 in combination, a die, meansadapted topass through said die for gripping a sheet metal strip, acylinder and piston supplied with a liquid to the rear of said die fordrawing said strip through said. die and means. for acting on the liquidin said cylinder with compressed air.

2; In a sheet metal tube drawing' plant in combination, a pair of dies,means adapted to pass through each die for gripping a sheet metal strip,a cylinder and piston supplied with a fluid to the rear of each die andmeans for causing said pistons to alternate in their movementsrelatively to said' dies and to move at varying speed. a

3. In a sheet metal tube drawing plant in combination, a pair of dies,means adapted to pass through each die for gripping a sheet metal strip,a cylinder and piston'supplied with a fluid to the rear of each die,means for causing 'saidpistons to alternate in their movementsrelatively .to said dies and to move at varying speed and means foracting on the fluid in said cylinders with "compressed air.

In testimony whereof I affix my signature.

GUsTaF ABRAHAM LINDGREN-y that I donot v

